Abstract
The changes in radiosensitivity during embryogenesis of the silkworm, Bombyx mori L. were investigated. The radiosensitivity expressed as LD50(R) values was estimated from the dose-hatchability curves obtained following irradiation with X-rays and 137Cs gamma-rays.
Data obtained in the present study together with results previously reported indicated that the radiosensitivity generally decreased as the embryonic development proceeded and that the age-dependent change in radiosensitivity may strongly depend on the degree of morphogenesis. From the viewpoint of the marked differential stage sensitivity, the process of embryogenesis may be divided into two main phases : one is a sensitive phase which corresponds to the time prior to and during blastokinesis (or before the completion of the embryonic morphogenesis) and the other is an extremely resistant phase which corresponds to the stage after blastokinesis. The former embryo was about 10 times as high in radiosensitivity as the latter embryo. The implication of these results was discussed.
